The present invention relates generally to sharp medical instruments such as syringes and needles, and more particularly to protecting users of such instruments from inadvertent injury from the instruments.
Adequately protecting physicians, nurses, and other medical staff users of sharp medical instruments has always presented a challenge. More recently, with the spread of AIDS, hepatitis, and other highly infectious diseases, it has become even more important to protect users of syringes, scalpels, and other sharp devices from injury and infections, especially in a health care facility. The Needle Stick Safety and Prevention Act passed unanimously in both houses in 2000, and thirty-five states have enacted legislation mandating protection to medical staff at such facilities from wounds or other injury resulting from use of such instruments. See for example State of California Labor Code xc2xa7144.7(d).
Various protective devices have been attempted in the prior art, but generally such devices have not functioned well, were not user-friendly, and generally have not been widely accepted, notwithstanding a need for such devices. Many prior art devices overlook the fact that when a medical practitioner uses such a device, a syringe for example, at best one hand is available to hold the device. For example, a nurse preparing a patient for an injection with a syringe requires one hand to clean the patient area to be injected, and one hand to hold the syringe while injecting the needle and syringe contents into the patient""s tissue. Upon injecting the syringe contents, the nurse will withdraw the needle from the patient with one hand, and typically will press a compress against the injection site with the other hand, to halt any flow of blood.
In typical prior art protective devices, the nurse or other medical practitioner must now use the free hand to twist a cover over the syringe or sharp portion of other medical device. Thus, one hand is required to hold the device while the other hand twists the protective prior art cover. In the interim, the needle portion of the device may drip blood onto the patient or the nurse, with resultant contamination. Further, unless great care is exercised while maneuvering the syringe to utilize the protective prior art cover, the skin of the medical practitioner may inadvertently be punctured, again with potentially serial adverse medical consequences.
An exemplary prior art protective device is disclosed in U.S. Pat. No. 5,885,257 to Badger (1999), a somewhat cumbersome device in which a compressed spring retracts a needle syringe into a holdable barrel after use, and wherein a second hand appears required to actuate the spring release mechanism. Unfortunately, during an injection when Badger""s spring is compressed, the needle may not extend sufficiently clear of the device to attain a proper injection depth. Further, Badger disclosed a notched plunger intended to be broken after use, to prevent reuse of the syringe. But if the plunger is not broken, the syringe is free to be reused, in violation of good medical practice and federal law. Further, the spring may urge the notched plunger so far rearward to allow blood or other fluid to escape from the rear end of the barrel.
Thus, there is a need for a protective device for a syringe or similar medical instrument that protects the instrument while allowing the instrument to be used with one hand. Such device should further prevent the instrument from being used after an initial use, and should adequately protect users from puncturing or otherwise wounding themselves with he instrument after it has been used. Finally, such device should prevent users against contamination from fluids within or in contact with the instrument.
The present invention provides such a device.
Applicant""s parent application disclosed a one-time useable needle-stick safety syringe that could be used with one hand. The syringe included an inner tubular body (body) with an extended needle at one end, and a plunger mechanism at the other end. A larger diameter protective outer tubular housing (housing) concentrically surrounded at least a portion of the body, and included a washer-like plug at the syringe plunger end and a washer-like collar with a cantilevered push-stop at the syringe needle end. The body was free to slide axially within the housing. A spring surrounded the plunger near the syringe plunger end to urge the housing toward the syringe needle end. Before use, the push-stop prevented the spring from urging the housing over the syringe needle end. After use, the person using the syringe would press the push-stop with a finger of the hand hold the syringe. This action allowed the housing to be urged by the spring over the syringe needle end. A slot in the housing near the syringe piston end then captured the push-stop, thus preventing reuse of the syringe, since the needle region was now surrounded by the housing. In this configuration, the syringe was safe in that the needle was protected; a person would literally have to insert a finger into the housing before contacting the needle.
The present invention advantageously further prevents an attempt to reuse the syringe by replacing the slot in the housing with a recess in the inner housing surface. Preferably the recess defines an annular shape such that regardless of any twisting between the push-stop and the syringe housing, the recess will always engage a portion of the push-stop when the housing surrounds the push-stop. After one use of the present invention, as the housing is urged toward the syringe needle end, the recess traps the push-stop completely within the housing, to prevent reuse. With this configuration, one cannot readily release the push-stop, even in a very deliberate attempt to reuse the syringe. Preferably the present invention now includes a second outer trigger that actuates the push-stop to promote more consistent and ready retraction. In addition, the present invention preferably disposes the compression spring within, rather than without, the syringe. Finally, the ridge and groove feature of the parent invention may be dispensed with to minimize friction when using the present invention.
Other features and advantages of the invention will appear from the following description in which the preferred embodiments have been set forth in detail, in conjunction with the accompanying drawings.